Method of grinding.



-G. I. ALDEN.

METHOD OF GRINDING.

APPLICATION FILED FEB. 11. 1910.

Patented Dec. 9, 1913.

2 SHEETSSHEET 1.

Inventor /1/a'/ne,6,5e,s.. ,5 W Ecorgefilclem 6. 1729 By 170 toi'neys. mSM G. I. ALDEN.

METHOD OF GRINDING.

APPLICATION FILED r2341, 1910.

1,081,082. Patented Dec. 9, 1913.

2 SHEETS-SHEET 2.

7?,Z17 aM GeorgeI/flden.

UNITED STATES, PATENT OFFICE.

GEORGE I. ALDEN, 0F WORCESTER, MASSACHUSETTS,'ASSIGNOR TO NORTONGRINDING COMPANY, OEWOROESTER, MASSACHUSETTS, A CORPORATION OFMASSACHUSETTS.

. METHOD OF GRINDING.

To all whom it may concern."

Be it known that I, Gnonon T. ALDEN, a citizen of the United States,residing at \l'orcester, in the couhty of Worcester and State oflvlassachusetts, have invented a new and useful Method of Grinding, ofwhich the following is a specification.

This invention relates to a method of grinding thin knife blade andcutter blanks. Blanks of this kind have been ground ordinarily by handon natural stones and any attempts that may have been made heretofore,so far as I am aware, to grind them automatically and particularly onartificial stones, have been commercially unsuccessful. This is due tothe fact that these blanks easily become burned when ground in this way,and no efi'ective means was known for avoiding it.

This invention is designed for the purpose of overcoming thesedifficulties and providing a practical method and efficient means foraccomplishing this result.

Reference is to be had to the accompanying drawings in which- Figure 1is a front elevation of a pre ferred form of machine for carrying outthis invention. Fig. 2 is a sectional view showing certain detailsthereof, and Fig. 3 is a plan showing a cutter in position for grindingand illustrating how the stream of water is applied thereto.

Several kinds of blades are manufactured from blanks which have squareedges that must be ground off to an acute angle before they are put uponthe market. This particularly 1s the case with mowing machine knives orcutters. So far as I am aware, such articles have ordinarily been groundin the shop practically by hand, that is, each blade is manipulated by aworkman on the surface of a natural grinding stone. Obviously, muchgreater speed and economy in production could be obtained if theseblades could be ground on artificial stones, as for example, emery orcorundum wheels which have a much more rapid cutting action than thenatural stones. Heretofore it has been regarded as commerciallyimpracticableto grind thin blades, such as mowing-machinecuttersections, upon such artificial wheels, by reason of the liabilityof burning the blades or drawing their temper, even when the blades werecompletely flooded by water. The object of the present invention is toSpecification of Letters Patent. Application filed February 11, 1910.Serial No. 543,298.

Patented Dec. 9, 1913.

provide an-apparatus and method whereby this difficulty may be overcome,so that an artificial grinding wheel, even of comparatively fine grain,may be used without danger of imury to the blanks. In order toaccomplish this result I have discovered that it is not sufficient tocool the blades in any way heretofore known, as flooding the blades withcold water under ordinary conditions will not carry away enough heat,and even the entire submersion of the blades in cold water would notcool them with sufficient rapidity when operated upon at high speeds byartificial grinding wheels.

of suitable fineness. I have discovered however, that the heat can becarried away by introducing cold water on the blades while being groundunder a high pressure and at a correspondingly high velocity anddirecting that water on the side of the blade opposite the wheel in afine stream along a line slightly back from the extreme sharp edge beingformed, and parallel thereto. I have found in practice that whenoperating upon ordinary mowing machine cutters, such as are nowmanufactured in large quantities in this country, if the steam isdirected in the manner above described, a pressure of from 100 to 150pounds per square inch is very suitable for the purpose. I believe thatone reason for the decidedly different result obtained by the use ofwater under pressure in this way is due to the fact that when the wateris applied to the blades in a comparatively quiescent state, the heat ofthe blank is sufficient to partially vaporize the water and cause minutebubbles or particles of vapor to adhere directly to the surface of theblade. The vapor as is well known is not as good a conductor of heat asthe water itself, and consequently, it tends to hold the heat. Byapplying the water under sufiicient pres sure to cause it to flow withcomparatively great rapidity, the vapor has no chance to form or if itdoes form it has no opportunity to cling to the surface of the blank,but is forced to more along the same. As soon as it is dislodged fromits original place of formation, it will move out of close contact withthe surface of the blade, so that the water can come into contact withthe metal. As no particle of steam can remain for any appreciable lengthof time in any place, the water has a chance to get at every part of thesurface of the blank. In this way, therefore, an eilicient cooling issecured, and-.it'has been amply demonstrated in practice that thethinjblanks can be ground 1nth1s'way on an emery or corundum wheel ofcome parative fineness at a yei'y high speed withou t danger of burning.

The invention is illustrated in a form in which a base 4 supports a tank5 in which are mounted'emery or other artificial grinding wheels 6. Thecutter blanks B are held on a table plate 7 in position for grinding by.plungers 8. The mechanism for operating the plungers does notconstitute a part of this patent but toggle levers 9 are shown. Twowheels are shown so that the blanks can be moved along the table platefrom one to the other and ground on both sides.

A pump 10 of any desired character is provided drawing water from anysource, preferably from a settling tank 11 and supplying it' to apressure tank 12 under considerable pressure. ample that a pressure of100 to 150 pounds per square inch is very suitable for this purpose.From this tank the water is forced through a pipe 13 into a pair ofdistributing pipes 14 through a valve 15'. From each of the pipes 14 itpasses by means of connections 16 into a chamber 18 in each of theplungers 8. The support for each plunger is provided with an elo atedpassage 19 for receiving the connection 16 in all positions of theplunger. The bottom of the. plunger is provided with'a long narrow slot20 by which the water issues 1n direct contact with the blank along aline a little back from the edge during the entire time during which theblank 1s being ground. In fact the cooling water under this heavypressure is dischar ed on the blade throughout the time while it is inposition so that in addition to cooling the blade it keeps the otherparts of the mechanism cool.

I have found in practice that by providing a flow of water under highpressure the heat is carried ofl with such rapidity that even with thinblanks of the particular temper required for mowing machines noappreciable burning or temper drawing takes place. The water isdischarged over the blades on the surface of the stones and issues froman opening'21 in the casin' 5. It then passes into the settllng tank were it is strained and settled so that the particles removed from thestones are left in the bot- I have found for ex-.

vention described nor ,to the exact use of the invention referred to butWhat I do claim is: 1. A method of grindin cutter blanks which consistsin applying t em to a grinding wheel and forcin a coolingliquid underhigh pressure and ve ocity against the blank on the side opposite thewheel in a thin stream along a line parallel with and at a shortdistance from the extreme edge being ground.

2. A method of grindin cutter blanks which consists in applying t em toa grinding wheel and forcing a cooling liquid under high velocityagainst the blan along a line parallel with the extreme edge beingground.

3. A method of grinding mowing machine knife-section blanks, whichconsists in applying first one ed e and then the other to a air of grining wheels, and

while the e ges are in contact with the wheels applying a thin stream ofwater under pressure near said edges.

4. A method of grinding blanks, which consists in applying the cuttingedge thereof to the surface of a quick cuttin grinding wheel, holdingthe blank in su stantially stationary position until ground, andconstantly forcing cooling fluid under pressure of more than one hundredpounds per square inch against the blank in a'thin stream parallelwit-h, and uniformly throughout the extent of, the cutting edge and at aslight distance therefrom,- in position to run the cutting edge on thewheel.

In testimony whereof I have hereunto set my hand, in the presence of twosubscribing witnesses.

GEORGE I. ALDEN.

Witnesses C. 0. SMITH, A. J. DUPRli.

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